The present invention relates to improvements in plural compartment containers for medicaments and the like and more specifically to that type of container adapted for temporarily isolating a compartment containing a solid pharmaceutical product from a compartment containing an aequeous solution for storage purposes and wherein the components may be readily admixed to use the medication.
Two compartment vials or containers wherein a medication and a solvent can be held in complete independence or isolation from each other until it is desired to use the medication are not new per se. Typical prior compartmented vials are illustrated for example, in Crankshaw, et al, U.S. Pat. Nos. 4,194,640, No. 4,089,432 and the Lockhart U.S. Pat. No. 2,869,745. These vials are generally of the same construction and comprise an hourglass shaped container made of glass having a movable stopper supported in the discharge end and a plug made of resilient material, such as rubber, frictionally force fitted in the constricted or reduced venturi center section of the container dividing the container into an upper chamber or compartment usually for the diluent or solvent and a lower chamber or compartment for the powder medicament. By this arrangement, the solvent and power medicament are isolated for good shelf life and now when it is desired to mix the two, the stopper in the discharge end is simply pressed inwardly to create internal pressure sufficient to displace the plug in the venturi of the container into the lower compartment to allow mixing of the solvent and powder medicament.
While these prior vial or container assemblies for medicaments are generally suitable for the purposes intended, there are nevertheless certain disadvantages and drawbacks which the present invention is designed to overcome. For example, it has been found that the center seal or plug is somewhat clumsy and difficult to assemble in place to provide the necessary hermetic seal between the diluent and the powder medicament compartments. Furthermore, because of the usually small size of this plug, and the variations and imperfections usually inherent in glass containers, the seal is usually not of a character to provide a good moisture-vapor barrier ensuring against breakdown of the product over an extended shelf life period. Furthermore, the stopper at the discharge end of the container has to be of a prescribed tight fit to ensure against leakage which would permit air bypass and thereby preclude displacement of the center plug when the outer stopper is pressed inwardly. Additionally in these prior assemblies, a portion of the outer stopper is exposed to the ambient atmosphere and may be contacted by the user. Thus when the stopper is displaced upon activation to a position where the medicament product may contact this portion of the stopper, there is the possibility of contaminating the medicament.
There are also prior syringe assemblies wherein the diluent and the powder medicament are maintained in separate isolated chambers for storage. These syringe assemblies typically comprise an outer barrel for the powder medicament and an inner barrel which telescopically fits into the outer barrel and has a plunger assembly with a rupturable diaphragm normally closing the open end thereof. When it is desired to activate the syringe, the plunger is pressed inwardly to rupture the diaphragm at the discharge end of the inner barrel and permit flow of diluent to the powder medicament in the outer barrel.
By contrast, the present invention provides a self-contained unit wherein the parts of the container or syringe contacting the diluent and powder medicament can be effectively sterilized and maintained in a sterile condition even after activation. To this end, the assembly includes an elongated barrel, a bypass piston slideably mounted in the barrel, and a plunger rod connected to the piston for movement of the bypass piston therein. The unit is easy to fill with the powder product and diluent. This is simply done by sealing the discharge end of the barrel, depositing the desired quantity of powder medicament into the bottom of the barrel and thereafter inserting the bypass plunger in the barrel to a predetermined depth just above the level of a powder medicament. The diluent is then added to fill the barrel above the bypass piston. The upper seal is then pressed in place and the assembly is ready for storage. When it is desired to mix the diluent and powder medicament, the plunger rod is simply withdrawn axially, whereby the diluent bypasses the plunger and the admixed product is now ready for use. Note that in this operation none of the elements of the assembly which are likely to be contacted by the user comes in contact with the diluent or powder product during reconstitution thereof. Furthermore, the bypass plunger is displaced by a fixed positive connection between the piston rod and bypass plunger and does not depend on displacement by build up of internal pressure as in the two compartment vials discussed above.
With the above in mind, it is an object of the present invention to provide a novel single barrel two compartment container assembly suitable for use in an intravenous administration set or as a syringe which is comprised of comparatively few parts and is fully effective in operation and use.
Another object of the present invention is to provide assembly wherein the diluent and powder medicament are maintained in a sterile environment prior to use and can be easily mixed in that same environment.
Still another object of the present invention is to provide a single barrel two compartment assembly for medicaments wherein the plunger arrangement ensures a positive seal providing an extended storage life and which is nevertheless relatively easily displaced to mix the contents when desired.
A further object of the present invention is to provide any single barrel two compartments arranged and comprised of relatively few parts which is simple and economical to manufacture and assemble.